Dep. of Crop and Weed Sciences, North Dakota State Univ., Fargo, ND 58105

Abstract

Abstract

Knowledge of legume N production and legumeffects on subsequent crop yield and quality is necessary to encourage legume use instead of the traditional fallow on set-aside land. Objectives of these studies were to: (i) compare seeding-year herbage and N yields five forage legume species, (ii) determine soil NO3-N status in the spring following green-manure legume crops, and (iii) evaluate effects of green-manure legumes on grain yield, grain yield components, and N nutrition of the subsequent wheat (Triticum aestivum L.) crop when fertilized with 0, 75, and 150 kg N ha−1. Field experiments were conducted on a Fargo silty clay (fine, montmorilloritic, frigid Vertic Haplaquoll) at Fargo and on a Perella-Bearden silty clay loam (fine-silty, mixed, frigid Typic Haplaquoll, fine-silty, frigid Aeric Caiciaquoll) near Prosper, ND, during 1984 to 1986. All legume species had equal herbage and N yields across the four environments and were greater than the wheat-straw check. Accumulated legume herbage and fall regrowth were incorporated into the soil in late fall. Spring soil NO3-N following Terra Verde alfalfa (Medicago sativa L.) and hairy vetch (Vicia villosa Roth.) was equal to the fallow check and greater than the soil NO3-N following the wheat check or other legume species. Grain yield, grain N, and N uptake of unfertilized wheat following the legume treatments generally were similar to those following fallow and wheat fertilized with 150 kg N ha−1. Increases in all grain yield components following legumes contributed to this yield advantage. Efficiency and utilization of N generally were greater following a green-manure crop than following either fallow or wheat checks. This study suggests that green-manure legumes should be considered as an alternative to fallow on set-aside land in higher moisture areas.

Research, supported in part by the North Dakota Agric. Exp. Stn., was dissertation by the senior author in partial fulfillment of the requirements for the Ph.D.

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